[U-Boot] FSL PCIe LTSSM >= PCI_LTSSM_L0 equals link up

[Mingkai Hu]

> -----Original Message-----
> From: York Sun
> Sent: Wednesday, September 06, 2017 11:37 PM
> To: Joakim Tjernlund <Joakim.Tjernlund at infinera.com>; Mingkai Hu
> <mingkai.hu at nxp.com>
> Cc: Xiaowei Bao <xiaowei.bao at nxp.com>; u-boot at lists.denx.de
> Subject: Re: FSL PCIe LTSSM >= PCI_LTSSM_L0 equals link up
> 
> On 09/05/2017 04:08 AM, Joakim Tjernlund wrote:
> > On Mon, 2017-08-28 at 17:14 +0000, York Sun wrote:
> >> +Xiaowei
> >>
> >> On 08/28/2017 10:09 AM, Joakim Tjernlund wrote:
> >>> On Mon, 2017-08-28 at 16:55 +0000, York Sun wrote:
> >>>> On 08/28/2017 09:48 AM, Joakim Tjernlund wrote:
> >>>>> FSL PCIe controller drivers before REV 3 has this test for link up:
> >>>>>      enabled = ltssm >= PCI_LTSSM_L0;
> >>>>>
> >>>>> We have a PCIe dev. that stays in LTSSM=0x51 (Polling Compliance)
> >>>>> when non ready for PCI transaktions. When FSL PCIe controller
> >>>>> tries to access this device, it hangs forever.
> >>>>>
> >>>>> Is LTSSM=0x51 really a "legal" state for link up?
> >>>>> If not, what is a suitable range(maybe LO <= ltssm <= L0s(0x27)) ?
> >>>>>
> >>>>>     Jocke
> >>>>>
> >>>>> BTW, the same test is valid in Linux too.
> >>>>>
> >>>>
> >>>> Jocke,
> >>>>
> >>>> I am not an expert on PCIe. Please if this thread is helpful,
> >>>
> >>> Me neither .. :)
> >>>>
> >>>>
> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatc
> hwork.ozlabs.org%2Fpatch%2F801519%2F&data=01%7C01%7Cyork.sun%40n
> xp.com%7Cf46ff5111ba04e631a9b08d4ee377ecc%7C686ea1d3bc2b4c6fa92cd
> 99c5c301635%7C0&sdata=n9%2B2NIjEvsMBCljRLHS6NVVN4ANa3nBGpwUjI4
> Od%2Bhs%3D&reserved=0.
> >>>
> >>> It mentions polling compliance but this driver already tests for:
> >>> if (ltssm < LTSSM_PCIE_L0)
> >>> 		return 0;
> >>> 	return 1;
> >>>
> >>> It just adds some delay if the device is in Polling Compliance to
> >>> see if that changes to L0.
> >>> Since both layerscape and fsl >= rev 3 already require ltssm to be
> >>> == L0, I suspect the ltssm >= L0 is bogus.
> >>>
> >>
> >> Xiaowei, can you comment?
> >>
> >> York
> >
> > Ping?
> > Should I just send a patch ?
> >
> 
> +Mingkai

LTSSM should be L0 state for linkup. Xiaowei have the patch to modify the code
for layerscape platform:
http://patchwork.ozlabs.org/patch/801519/ 

He will work out a patch for PowerPC platform also.

Mingkai